A puffer type gas insulated circuit breaker has releasably engaging stationary and movable arc contacts contained in a vessel filled with an arc extinguishing gas. An operation rod serving as a supporting member of the movable arc contacts has openings and helps define a puffer chamber. In the breaker, gas is pressurized by an arc generated between said stationary arc contacts and said movable arc contacts in an initial breaking phase, this gas being taken into the puffer chamber. The holes are used as a heat exhaust passage.
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